Science (Living Organisms)

• Characteristics of living organisms

  • Nutrition
  • Cellular respiration
  • Excretion of wastes
  • Response to surroundings
  • Movement
  • Control of internal conditions
  • Reproduction
  • Growth and development
• Autotrophs


  Organisms that have the ability to produce their own food
• Heterotrophs


  Organisms that eat other living organisms (plants or animals) and derive their energy from this food
• Types of heterotrophs


  • Herbivores
  • Carnivores
  • Omnivores
• Cell respiration


  The process that releases energy that is locked within substances such as glucose

  
• Respiration


  The process where the exchange of gases such as carbon dioxide and oxygen using the lungs or other respiratory organs occurs
• Aerobic respiration


  The process by which cells use oxygen to break down organic molecules, such as glucose, into carbon dioxide and water, releasing energy in the form of ATP

  
• Anaerobic respiration


  The process by which cells extract energy from organic molecules without using oxygen
• Anaerobic respiration in muscle cells

  Leads to production of lactic acid
• The build up of lactic acid causes muscle pain, which is then carried by the blood to the liver where it transforms back into glucose and can be stored/reused by the body</b>
• Photosynthesis and cellular respiration are opposite processes
• Excretion


  The process of removing waste products from cells
• Egestion


  The elimination of feces from the body
• Tropism


  A growth toward or away from a stimulus
• Homeostasis


  The maintenance of the internal environment of an organism within required limits
• Types of reproduction


  • Asexual
  • Sexual
• Meiosis


  A special type of cell division in which the gametes, also called sex cells, are produced
• Mitosis


  A type of cell division in which a cell divides into two daughter cells that are identical to the parent cell
• Eukaryotes and prokaryotes are the two main domains of living organisms
• Plants, bacteria and fungi have different cell wall compositions
• Plants and animals store their excess sugars differently
• Key vocabulary


  • cellulose
  • glycogen
  • peptidoglycan
  • hitin
  • mycelium
  • hyphae
  • saprotrophic
  • protozoa
• Pre-history gives us an overview of life from its possible origins, perhaps 3.5 billion years ago
• Scientists have placed together the probable beginning of life to the diversity of living organisms we see on Earth today
• Today's world has an enormous diversity of living organisms
• To make sense of all this information, we find it useful to sort or classify them into groups
• The tree of life evolution diagram

  • Shows a sequence with branches, reflecting relationships between different groups and how they have changed or diverged over time
• Five kingdom classification


  Monera, Protista, Animalia, Fungi, Plantae
• Plants and animals


  • Both are multicellular organisms
  • Plants contain chloroplasts and carry out photosynthesis
  • Plants have cellulose cell walls
  • Plants store carbohydrates as starch or sucrose
  • Animals do not contain chloroplasts and do not carry out photosynthesis
  • Animals do not have cellulose cell walls
  • Animals often store carbohydrates as glycogen
  • Animals usually have nervous coordination
  • Animals are able to move from place to place
• Plants


  • Maize (a cereal)
  • Peas (a herbaceous legume)
• Animals


  • A horsefly (an insect)
  • A human
• Cellulose


  A complex sugar molecule, consisting of hundreds – and sometimes even thousands – of carbon, hydrogen and oxygen atoms, that is the main substance in the walls of plant cells, helping plants to remain stiff and upright. Humans cannot digest cellulose, but it is important in the diet as fibre.
• Starch


  A complex carbohydrate produced by plants, with glucose as its basic subunit
• Glycogen


  A complex carbohydrate found in animals, with glucose as its basic subunit
• Sucrose


  Also known as simple sugar, made from one glucose and one fructose molecule, with chemical formula C12H22O11
• Fungi


  • Cannot carry out photosynthesis
  • Have cell walls made of chitin
  • Their body is made up of threadlike hyphae, containing many nuclei and organised into mycelium
  • They feed by secreting extracellular digestive enzymes (outside of the mycelium) onto the food and then absorbing the digested molecules
  • This method of feeding is described as saprotrophic (feeding on decaying matter)
  • They sometimes store sugars in the form of glycogen
• Chitin


  A complex carbohydrate that is part of the structure of fungi
• Mycelium


  A mass of branched, tubular filaments (hyphae) of fungi, building the body of the typical fungus
• Bacteria


  • Are single-celled organisms that have different shapes
  • Their cell structure includes cell wall, cell membrane, cytoplasm and plasmids
  • They have no nucleus but contain circular chromosome of DNA
  • Some can carry out photosynthesis
  • Most feed of other organisms (living or dead), with decomposers feeding on the dead and parasites feeding on the living
  • Their cell wall is made from peptidoglycan, a molecule composed of sugars and amino acids
• Bacteria


  • Escherichia coli (bacteria living in the intestines of humans)
  • Streptococcus pneumoniae (bacteria causing pneumonia in humans)
  • Bacillus anthracis (bacteria causing anthrax a deadly disease in humans and animals)